No trigger that's obvious to me.
Often in the script editor but that's where I am much of the time anyway.
It's also happened a few times while trying to turn sound or media on or off, but I've had recurrent modal dialogs about SLPlugin.exe exits for a couple years so that's all probably unrelated to what's been happening with this specific release.
Log says:
2026-08-06T11:30:27Z WARNING # llcommon/llwatchdog.cpp(291) LLWatchdog::run : Watchdog timer for thread WindowThread: 43628 expired with state: messages; assuming viewer is hung and crashing